Eddy Correlation Measurments of Snow-Atmosphere Exchange of N0y and Water Vapor at Summit (Greenland)

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This is one of four coordinated projects that will make use of the camp facilities established on the ice sheet in the interior of Greenland as part of the GISP-2 ice core drilling effort, in order to investigate how atmospheric trace elements are deposited on the ice and what kind of changes they undergo as they are being incorporated into the ice. An understanding of such processes is necessary in order to properly interpret the proxy climate data that can be recovered from ice cores. While significant progress has been made recently in extracting and analyzing ice cores, progress in understanding the air to snow transfer process for reactive chemical species has lagged behind. The goal of this project is to determine the vertical fluxes of reactive nitrogen oxides, water vapor, sensible heat, and momentum. through a field measurement program in 1994 and 1995. A specific objective is to define the transfer function between reactive nitrogen oxide concentrations in the atmosphere and in the snow, thus allowing the interpretation of the nitrate record in ice cores in terms of changes in atmospheric photochemistry and in the biogeochemical cycling of nitrogen. Other objectives are to determine the environmental variables regulating the exchange of reactive nitrogen oxides between air and snow, to assess the relative importance of dr and wet deposition and reevaporation in controlling the nitrate accumulation, and to analyze the meteorological conditions controlling the supply of nitrates to the ice sheet.